1. Field of the Invention
The present invention relates to a process and apparatus for finely crushing or milling particulate mineral material, such as ores.
2. Description of the Prior Art
French patent application publication No. 2,620,635, published Mar. 24, 1989, discloses a process and apparatus for milling particulate mineral material, wherein a layer of the material is subjected to compression in a space between two cylinders rotated in opposite directions about parallel axes defining a plane and yieldingly pressed against each other. The rotation of the cylinders force-feeds the material into the nip between the cylinders where it is milled, and the outlet space below the plane is partially closed off to keep the milled material under pressure, only an outlet passage of reduced cross sectional area being left open for discharge of the milled material. The back pressure exerted on the material being milled in the nip between the cylinders causes the particles to be de-cohered as a result of the generated shearing forces caused by the anisotropy of the layer of the material being milled in the nip, and counteracts the formation of agglomerates.